Welcome to Eel World

Anthropocene Information

The eel is a long, thin bony fish of the order Anguilliformes. Because fishermen never caught anything they recognized as young eels, the life cycle of the eel was a mystery for a very long period of scientific history. Although more than 6500 publications mention eels, much of their life history remains an enigma. The European eel (Anguilla anguilla) was historically the one most familiar to Western scientists, beginning with Aristotle, who wrote the earliest known inquiry into the natural history of eels. He speculated that they were born of "earthworms", which he believed were formed of mud, growing from the "guts of wet soil" rather than through sexual reproduction. Many centuries passed before scientists were able to demonstrate that such spontaneous generation does not occur in nature. Other early scientists believed that the eelpout Zoarces viviparus was the "mother of eels" (the translation of the German name "Aalmutter"). No one yet knows the reasons, but beginning in the mid-1980s, glass eel arrival in the spring dropped drastically — in Germany to 10% and in France to 14% of their previous levels — from even conservative estimates. Data from Maine and other North American coasts showed similar declines, although not as drastic. In 1997, European demand for eels could not be met for the first time ever, and dealers from Asia bought all they could. The traditional European stocking programs could not compete any longer: each week, the price for a kilogram of glass eel went up another US$30. Even before the 1997 generation hit the coasts of Europe, dealers from China alone placed advance orders for more than 250,000 kg, some bidding more than $1,100 per kg. Asian elvers have sold in Hong Kong for as much as $5,000 to $6,000 a kilogram at times when $1,000 would buy the same amount of American glass eels at their catching sites. Such a kilogram, consisting of 5000 glass eels, may bring at least $60,000 and as much as $150,000 after they leave an Asian fish farm. In New Jersey, over 2000 licenses for glass eel catch were issued and reports of 38 kg per night and fisherman have been made, although the average catch is closer to 1 kg. The demand for adult eels has continued to grow, as of 2003. Germany imported more than $50 million worth of eels in 2002. In Europe, 25 million kg are consumed each year, but in Japan alone, more than 100 million kg were consumed in 1996. As the European eels become less available, worldwide interest in American eels has increased dramatically. New high-tech eel aquaculture plants are appearing in Asia, with detrimental effects on the native Japanese eel, A. japonica. Traditional eel aquaculture operations rely on wild-caught elvers, but experimental hormone treatments in Japan have led to artificially spawned eels. Eggs from these treated eels have a diameter of about 1 mm, and each female can produce up to 10 million eggs. However, these treated eels may not solve the eel crisis. Scientists are struggling to get eels to sexual maturity without environmental cues.Additionally, leptocephali (larva) require a diet of marine snow which is difficult to recreate in aquaculture.

In 2010, Greenpeace International added the European eel, Japanese eel, and American eel to its seafood red list. Japan consumes more than 70% of the global eel catch. Strong concerns exist that the European eel population might be devastated by a new threat: Anguillicola crassus, a foreign parasitic nematode. This parasite from East Asia (the original host is A. japonica) appeared in European eel populations in the early 1980s. Since 1995, it also appeared in the United States (Texas and South Carolina), most likely due to uncontrolled aquaculture eel shipments. In Europe, eel populations are already from 30% to 100% infected with the nematode. Recently, this parasite was shown to inhibit the function of the swimbladder as a hydrostatic organ.As open ocean voyagers, eels need the carrying capacity of the swimbladder (which makes up 3–6% of the eel's body weight) to cross the ocean on stored energy alone. Because the eels are catadromous (living in fresh water but spawning in the sea), dams and other river obstructions can block their ability to reach inland feeding grounds. Since the 1970s, an increasing number of eel ladders have been constructed in North America and Europe to help the fish bypass obstructions. In New Jersey, an ongoing project monitors the glass eel migration with an online in situ microscope. As soon as more funding becomes available, it will be possible to log into the system via a Long Term Ecological Observatory (LEO) site.No one yet knows the reasons, but beginning in the mid-1980s, glass eel arrival in the spring dropped drastically — in Germany to 10% and in France to 14% of their previous levels — from even conservative estimates. Data from Maine and other North American coasts showed similar declines, although not as drastic.